Steam-engine valve mechanism.



1101827433. PATENTEYD JULY a1, 1906.

P. VPOSDIGK. I STEAM ENGINE VALVE MECHANISM.

7 APPLICATION FILED JAN. 24, 1906.

1H: NORRIS PETERS cm, wasumaron, n. c.

'- To all whom it mayconcern:

. UNI ED STATES PATENT OFFICE.

FREDERICK EosD1o'K,'oE FITCHBURG, MASSACHUSETTS.

Application filed January 24,1906. Serial No. 297.666.

. which thefollowing description, in connec- I rest of dam adapted tokeep the valvemoving tion with the accompanying drawings, is aspecification, like numerals on the drawings representing like parts. ia

This invention relates to steam-engine valve mechanisms, and especiallyto the valve mechanism of the type shown in my Patent No. 569,628, datedOctober 20, 1896.

The valve mechanism shown in said'patent comprises a reciprocating camconnected to" the valve proper and provided with a camsurface which isactedupon by an oscillating arm carrying a pin. The cam-surface in thereciprocating cam is in the form of a cam-slot,

which for the reater part of its length is concentric with t e axis ofmotion of the oscillating arm and which terminates at one end in anoffset portion that is engaged by the pin on the oscillating arm .togive the valve its motion. With this construction the valve remains atrest during the time that the pin on the oscillating arm is moving throuh the concentric portion of the slot, and t e movement of the valvecommences and continues while the pin on said arm is in engage,- mentwith the ofiset portion of said slot. I have found that when a valvemechanism such as shown and described in said patent is used in a mediumor high speed engine where the valve makes a very quick stroke thechanging of the valve from its condition of rest to its sliding movement1s accomplished in so short atime that there is considerable shock orjar developed-in the running of the engine, this shock or jar being es-]pecially a parent inlarge engines running at 'gh spec and having comaratively heavy va ves. In order to avoid t 's shock and jar so that thevalve will be gradually started and radually brou ht to; its. conditionof I have provide a special construction throughout the entire movementof the rocking arm, the movement of the valve during the first part of.the movement of the rocking arm'being very sli ht, but suflicient toovercome its inertia, so t at when the, arm engages the offset portionof the cam to" give the valve its movement the valve is startedfromiafmoving condition. .One convenient Specification of LettersPatent.

a valve-r0 STEAM-ENGINEVALVE MYEVCHAINISM.

.Pat ented July 31, 1906.

way of making the cam-surface to accofmplish this end .is to make thegreater part thereof sufiiciently eccentric-so that the valve will havea slight initial movement before the pin on the rocking arm engages theoflset portion 'of the cam-slot.

" In the drawings, Figure I is a side view of one cylinder 'of an enginehavin my improved valve mechanism applied thereto, part ofthevalve-chest being broken out to better show the construction; and Fig. 2is an 8' is a rocking or oscillating arm provided with a pin 10, whichengages the cam-slot 7 and another arm 8, which'is connected by a link11 with the corresponding arm 8 for the valve at the other end of thecylinder. These two rockin arms 8 are suitably connected to d 12, whichis actuated by the usual eccentric mechanism for operating the valves. i

- The parts thus far described are similar in their constructionand'operation to the corparts in the above-mentioned respondin patent.In said patent, however, the camslot 7 is for the greater ortion of itslength concentric with the ro'c -shaft 9 and at its upper end isprovided with an offset portion. With this construction during thetime-that the pin 10 of the oscillating arm is moving in the concentricportion of the slot the valve remains at rest,.said valve receivingmotion only when said 'pin en ages the offset ortion of the cam-slot. Vhsuch as shown in the above-mentioned patent is used in medium-speed orhigh-speed engines, the valve issuddenly started from a condition ofrest at the time when the pin 10 passes'from the concentric to theoffset portion of'the slot, this sudden starting and stoppin of thevalve occasioning more or less un esirable shock and jar. To avoid this,I make the slot 7 for the greater portion of its length slightlyeccentric to the-rock- Whichthe pin 10 travels in moving from the erethe mec anjsm' IIO full-line to the dotted-line position, Fig. 2', thiseccentricity being such that in moving from the full to the dotted lineposition the cam 6, and consequently the valve 3, is moved slightlytoward theleft, as shown in dotted lines, Fig. 2. When, therefore, thepin enters the offset portion 14 of the slot, thereby to give the valveits stroke, said valve is already moving and the change from the slowinitial movement to the quick working stroke of the valve may beaccomplished smoothly, evenly, and without any shock or jQar.

In order that the initial movement which the valve gets while theoscillating arm is moving from the full to the dotted line position maynot result in openin the valve too wide or sooner vthandesired, Iconstru'ct said valve with sufiicient lap, as shown at 15, to-

counterbalance this initial movement, so that said initial movementmerely results in covering the lap of the valve and in putting it in thesame position relative to thesteamports when the pin 10- is in thedotted-line position, Fi 2, as said valve is in its neutral position int e above-mentioned patent.

I have found that by constructing valve mechanisms as above describedlarge valves of highspeed en ines may be operated evenly and smooth yand with entire absence of all detrimental jar and shock occasioned bythe sudden starting and stopping of the valves.

Having fully described my invention, what I claim as new, and desire tosecure by Letters Patent, is

1. In a valve mechanism, a valve, a sliding cam connected thereto andhaving a camslot, and an oscillatin arm having a pin engaging said slot,said s ot for the greater portion of its extent being slightly eccentricto the pivot of said rocking arm and provided at one end with an offsetportion.

2. In a valve mechanism, a valve, a reciprocating actuator connectedthereto, an oscillating arm, and connections between said arm and theactuator to give the latter a slow initial movement sufliciently toartially overcome the inertia thereof ando the valve without opening thelatter during the first part of the movement of the arm, and a quickextended movement to open the valve during the last part of the movementof said arm;

In testimony whereof I have signed my name to this specification in: thepresence of two subscribing witnesses.

FREDERICK FO'SIDICK.

Witnesses W. A; ROBBINS, W. IVAN HARRISON.

